HTML5 Video is coming to Opera 10.5. Yesterday (or technically, last year--happy new year readers!) Opera released a new alpha build containing a preview of their HTML5 Video support. There's a number of details to note, not least that this is still an early alpha...

Every contributor (Apple, Nokia, GNOME, Google) does. WebKit makes no releases. The main development branch in never frozen for any release. WebKit makes no releases. "
The problem is that in practice, Webkit based browsers are a bunch of incompatible foreks: